Hi, tbh most of the course that are out there, like the 1/2 days are ment for compete newbs. Mainly enthusiastic DIYers or if you want to gain some knowledge and tips about using Lime. Most Lime knowledge is still passed on through firms and there apprentices. If you've never used Lime id recommend doing a course but if not lots of reading books and watching videos is other option. Experience is the big factor with Lime. It's been around for years and not something you just can pick up after a few days or weeks course. The skills are not much different to modern plastering it's just the prep work and aftercare of the Lime that is essential. Lime really is a complete field in itself. Where are the course you've been looking at?